A variety of techniques can be used to control an animal's behavior. For example, dog trainers ordinarily teach dogs by a repetition and reward technique to, among other things, obey commands, compete in shows or races, work in law enforcement, protect property, perform tricks, and guide people who are visually impaired. But sometimes it may be necessary to interrupt undesirable behavior as it is occurring in order to correct it, and sometimes one technique may work on one animal and not work on another animal.